Sorry.  My entry is missing some parts

I wouldn't refer to ''today" as ''the weekend"  since a weekend is not one, single day. I would say " today is Saturday" or  "today is Sunday.
"
I don't know why I've been so tired for the past few weeks (see my note above about the Present Perfect)

vocation = 职业
vacation = 假期

I hope everything goes well during the holidays.

Weekend

Today is weekend!I'm so happy to stay at home with my family.I donnot know why it's so tired for last few weeks,and i want to have a short vocation to relax.Hope everything go well during holiday.

We use the Present Perfect to say that an action happened at an unspecified time before now. The exact time is not important. You CANNOT use the Present Perfect with specific time expressions such as: yesterday, one year ago, last week, when I was a child, when I lived in Japan, at that moment, that day, one day, etc. We CAN use the Present Perfect with unspecific expressions such as: ever, never, once, many times, several times, before, so far, already, yet, etc.

Weekend

Today is weekend!I'm so happy to stay at home with my family.I donot know why I was so tired during last few weeks,and i want to have a short vacation to relax.Hope everything goes well during holiday.

btw:hope u a nice weekend~

Weekend

Today is weekend! I'm so happy to stay at home with my family. I donnot  don't know why it's I have been so tired for the last few weeks, and I want to have a short vacation to relax. (I prefer the word "holiday". "Vacation" is more American) Hope everything go well during holiday. (I'd say "I hope to have a good holiday").

Good! Bu cuo!